Senior LevelDB Expert needed for solving cache LOCK issue

We need a senior LevelDB expert to optimize our LevelDB and solve "Cache LOCK" issue. Our script saves some data to cache. When there are enough items in the cache, those items will be flushed to MySQL as batch and deleted from the cache. First, we used LevelDB for cache. LevelDB is super fast so it saves time writing to cache. But the thing is LevelDB doesn’t support for clear items, so the workaround for clearing items was close the opened cache, delete the whole cache folder and create new cache. But since this is not stable way, the “cache LOCK” issue happens. We have tried several ways to fix the cache LOCK issue with LevelDB but they all seem not efficient as the error keep happening. Then recently we switched to use SQLite for data cache. SQLite is fast, but in compare with LevelDB it’s still slower. We strongly prefer to use LevelDB on our script yet we have to solve this "cache LOCK" issue.